1. Field of the Invention
This invention relates to a pipe for a cooling unit to evaporate working liquid in a heat exchange system of heat pipe type, a cooling unit using such pipe and an individual cooling system capable of cooling each exothermic apparatus (Office Automation apparatus and information apparatus or the like) installed on one floor or each individual space.
2. Description of the Prior Art
Conventionally, a pipe for use in this kind of cooling unit has an evaporating portion c formed of a single pipe as shown in FIG. 2.
In case where the prior art pipe for the cooling unit as shown in FIG. 2 is used with the evaporating portion c vertically held or largely inclined to the horizontal direction, since the evaporating portion c is formed of the single pipe, working liquid a successively boils up inside the evaporating portion in high heat flow of the working liquid. Accordingly, the thermal conductivity is made high. However, as the intense heat flow is reduced, bubbles b resulting from the boiling of the working liquid a stay on the level of the working liquid a within the evaporating portion c to produce the distribution of temperature of the working liquid a in the evaporating portion c, so that the thermal conductivity is remarkably reduced.
Thus, the boiling of the working liquid a in the evaporating portion c becomes intermittent with the lapse of time, and the operation becomes extremely unstable to further reduce the thermal conductivity.
Generally, in the cooling unit of a heat exchange system of heat pipe type, the level of the working liquid a within the evaporating portion c should be set as high as possible in order to facilitate the boiling, and the quantity of working liquid a to be enclosed inside the evaporating portion is increased by the quantity corresponding to the elevated level, so that the start of the whole system takes a long time until the system is stationarily operated.
Also, in case where one floor is partitioned into a plurality of spaces by partitions, and an exothermic apparatus or the like is installed in each of the partitioned spaces, when each space is individually cooled down by a heat exchange system of separate heat pipe type, the heights of portions to be individually cooled from the floor surface are often different from each other, and it has been impossible for each cooling unit using the prior art pipe as shown in FIG. 2 to individually cool down the portions different from each other in height from the level of the working liquid while maintaining the levels of working liquid of respective cooling units on the same floor to be identical with each other. As a result, there has not yet been proposed a system for individually cooling down a plurality of individual spaces on the same floor while performing the heat exchange through a heat pipe system.